You want to install Gnome as your desktop window manager on OpenBSD?
Simply install gnome-session package using pkg_add tool.
In my previous article, I showed you how to set PKG_PATH to an ftp server nearest to you. It must be set first to install any packages on the fly (directly from an ftp server).
OK lets go ahead install gnome-session using pkg_add:

$ sudo pkg_add gnome-session

It will check the dependencies and install them first. Wait for some minutes to all the packages installed successfully.

After gnome-session package installation completed, you have to create/edit .xinitrc file in your home directory and contain only one line ‘exec gnome-session’.

$ echo "exec gnome-session" > ~yourhomedir/.xinitrc

It will make gnome-session as your default window manager.
Run ‘startx’ and you will see gnome-session starting.

To run gdm at boot, write these codes below into /etc/rc.local file:

if [ -x /usr/local/sbin/gdm ]; then
	echo -n ' gdm';		/usr/local/sbin/gdm
fi